SPI-NOR flash devicetree error int_res==16 EBUSY

[Joanna]

Dear Nordic Team,

I found a few similar issues in this forum but nothing that then solved my problem which brought me to the conclusion it might be different here.

I try to add an external SPI-NOR flash (MX25R8035F) to nrf52832 project. I started with the example in zephyr/samples/drivers/spi_flash which is for nrf52840 and changed the dts file as follows:


Here I post the "arduino-spi", I also tried with SPI0 and SPI1, same behavior.

nrf52dk_nrf52832.dts:

aliases {
 ...

 ...
spi-flash0 = &mx25r80;
};

arduino_spi: &spi2 {
status = "okay";
cs-gpios = <&gpio0 20 GPIO_ACTIVE_LOW>;
pinctrl-0 = <&spi2_default>;
pinctrl-1 = <&spi2_sleep>;
pinctrl-names = "default", "sleep";

mx25r80: mx25r8035f@0 {
compatible = "jedec,spi-nor";
label="MX25R80";
reg = <0>;
spi-max-frequency = <33000000>;
size = <0x800000>;
jedec-id = [c2 28 14];
};
};

my code:

const struct device *flash_dev = DEVICE_DT_GET(DT_ALIAS(spi_flash0));

void main(void)

{

    if (!device_is_ready(flash_dev)) {

        printk("%s: device not ready.\n", flash_dev->name);

    }

    ...

}

The problem:
The flash device gets partly  initialized since flash_dev.state.initialized == 1 and partly not since flash_dev.state.init_res==16 (should be 0). That is why device_is_ready() return false.
I see this in the debugger as below:

I see on my oszilloscope that SPI itself is working because I get responses from the external flash, so I can't be doing everything wrong. But the write and read process is working incorrectly, meaning that if I write something to a location, I get a wrong response when reading again.

Do you have any ideas what the problem could be? 
I also tried to research what EBUSY in the devicetree means in general and found that it often has to do with wrong pins. However, this can't be the case here, since my SPI is working, do you agree?

Thank you very much in advance,
Joanna

[Simonr]

Hi Joanna

From looking at this snippet from your .dts I'm not able to tell what's wrong. Is there a reason you've set the max SPI frequency to 33 MHz? I think this is higher than what the nRF52832 allows, and recommend going down to 8MHz.

Can you share what pins you're using for SPI in your application, the CS pin seems to be fine (as long as P0.20 isn't also used for something else in your application). When writing and reading data using SPI, what return values do you get when trying to read back for example? Is it just random garbage values or does it resemble at all resemble the data you wrote onto the flash?

Best regards,

Simon

[Joanna]

Hi Simon,

thank you for your answer!

1) no, there was no reason for 33 MHz, that was copied from the example. I set it down.

2) I tried SPI 1 and 2  in the devicetree (both with Pin 0.20 as CS) and have the same behavior

spi1_default: spi1_default {
group1 {
psels = <NRF_PSEL(SPIM_SCK, 0, 31)>,
<NRF_PSEL(SPIM_MOSI, 0, 30)>,
<NRF_PSEL(SPIM_MISO, 0, 29)>;
};
};

spi2_default: spi2_default {
group1 {
psels = <NRF_PSEL(SPIM_SCK, 0, 25)>,
<NRF_PSEL(SPIM_MOSI, 0, 23)>,
<NRF_PSEL(SPIM_MISO, 0, 24)>;
};
};

3) I get random garbage back for flash_read(flash_dev, SPI_FLASH_TEST_REGION_OFFSET, buf, len);
Interestingly, after an erase, I read 0xFF which is correct. Only after writing, I read the garbage. Maybe that is a hint? 

4) flash_read_jedec_id(flash_dev, &id) sometimes returns the correct first byte and then garbage, sometimes all garbage. 

This is all happening although flash_dev is not initialized correctly and device_is_ready(flash_dev) returns false. Still init_res == 16 as described above.

Regards,
Joanna